In addition to the 16s limit in per-response change in the monotonic
offset, don't allow the total accumulated offset injected in sourcestats
to be larger than 16 seconds.
Calculate the delay since the previous transmission only if the
TX timestamp is actually set. This removes an unnecessary delay when
starting at the Unix epoch in 1970 (e.g. in a test).
Don't ignore the magic field when searching for the exp1 extension
field in a received response. If there were two exp1 fields in the
packet, and only one of them had the expected magic value, it should
pick the right one.
Fixes: 2319f72b29 ("ntp: add client support for experimental extension field")
If the xleave option is enabled, ignore the key option and the hash
length. Always use version 4 as the default to get interleaved responses
from new chrony servers.
The interleaved modes are being specified for NTPv4 only. As a server,
detect interleaved requests only in NTPv4 packets.
Clients and peers can still send interleaved requests in lower-version
packets if configured with the version option.
Frequency transfer and time smoothing are conflicting features. Set the
monotonic timestamp in the experimental extension field to zero
(invalid) if time smoothing is activated.
Add "extfield F323" option to include the new extension field in
requests. If the server responds with this field, use the root
delay/dispersion and monotonic timestamp. Accumulate changes in the
offset between the monotonic and real-time receive timestamps and use
it for the correction of previous offsets in sourcestats. In the
interleaved mode, cancel out the latest change in the offset in
timestamps of the previous request and response, which were captured
before the change actually happened.
Maintain a server monotonic timescale needed for the experimental
extension field. It follows the best estimate of frequency without
time corrections. Implement it as an offset relative to the NTP time,
starting at zero, using a slew handler to cancel time corrections of the
NTP clock. The 32-bit epoch ID is set to a random value on start and
every step of the system clock.
Add an experimental extension field for some features that were proposed
for NTPv5. Higher-resolution root delay and dispersion (using 28-bit
fraction) are added. A monotonic receive timestamp will allow a
frequency transfer between the server and client. The client will be
able to separate the server's time corrections from frequency
corrections by tracking the offset between the real-time and monotonic
receive timestamps.
The field has a type of 0xF323 from the new experimental range proposed
by the NTP working group. Include a magic 32-bit value in the field to
avoid interoperability issues if a different implementation choses the
same type for its own experimental field. The value will be changed on
incompatible changes to avoid issues between two different chrony
versions.
Add a new variable to the packet info structure with flags for extension
fields included in received packets and add a new parameter to
transmit_packet() to add the fields to transmitted packets.
Since commit fdfcabd79b ("ntp: drop support for long NTPv4 MACs"), the
parser doesn't need to check validify of MACs in NTPv4 packets to
distinguish them from extension fields. Move the parser to ntp_core to
avoid having a separate iteration looking for non-authentication
extension fields.
When calculating the root delay and dispersion of a sample measured in
the interleaved mode, use the root delay and dispersion values from
the previous response (to which the TX timestamp corresponds). If the TX
timestamp is combined with the RX timestamp of the latest response (e.g.
in the symmetric mode), use the maximum of the previous and latest root
delay/dispersion.
When the server clock was updated between saving of the RX timestamp and
updating the TX timestamp, a client using interleaved mode with the four
timestamps which minimize error in measured delay (e.g. chrony) had the
server clock adjustment included in the measured delay, which could
disrupt the sample filtering and weighting.
Add a handler to track the slew epoch and remember the last offset. Undo
the adjustment in TX timestamps which have their RX timestamp in the
previous epoch to fix the delay observed by the clients.
If an unknown clock step is detected, drop all timestamps.
Don't save server RX and TX timestamp to clientlog if the transmission
or authentication failed (e.g. packet is handled in ntp_signd). They
will not be needed.
Zero the initial TX timestamp which is saved for the interleaved
mode in case there is no previous timestamp saved in clientlog and
transmit_packet() does not generate a new one (e.g. due to failure in
authentication).
Fixes: 5f4cbaab7e ("ntp: optimize detection of clients using interleaved mode")
When responding to a request, don't waste time with TX timestamping
if the timestamp will not be saved (i.e. clientlog is disabled).
Fixes: 5f4cbaab7e ("ntp: optimize detection of clients using interleaved mode")
Use the lowest bit of the server RX and TX timestamp as a flag
indicating RX timestamp. This allows the server to detect potential
interleaved requests without having to save all its RX timestamps. It
significantly reduces the amount of memory needed to support clients
using the interleaved mode if most of the server's clients are using the
basic mode (e.g. a public server).
Capture the TX timestamp on the first response to the request which has
the flag set to not further delay the first interleaved response.
False positives are possible with broken clients which set the origin
timestamp to something else than zero or the server RX or TX timestamp.
This causes an unnecessary RX timestamp to be saved and TX timestamp
captured and saved.
Move the calls resetting and generating authentication data out of the
loop checking for unique TX timestamp. This allows the timestamps to be
manipulated after the check.
Instead of keeping one pair of RX and TX timestamp for each address, add
a separate RX->TX map using an ordered circular buffer. Save the RX
timestamps as 64-bit integers and search them with a combined linear
interpolation and binary algorithm.
This enables the server to support multiple interleaved clients sharing
the same IP address (e.g. NAT) and it will allow other improvements to
be implemented later. A drawback is that a single broken client sending
interleaved requests at a high rate (without spoofing the source
address) can now prevent clients on other addresses from getting
interleaved responses.
The total number of saved timestamps does not change. It's still
determined by the clientloglimit directive. A new option may be added
later if needed. The whole buffer is allocated at once, but only on
first use to not waste memory on client-only configurations.
When separate client and server instances of chronyd are running on one
computer (e.g. for security or performance reasons) and are synchronized
to each other, the server instance provides a reference ID based on the
local address used for synchronization of its NTP clock, which breaks
detection of synchronization loops for its own clients.
Add a "copy" option to specify that the server and client are closely
related, no loop can form between them, and the client should assume the
reference ID and stratum of the server to fix detection of loops between
the server and clients of the client.
Don't update the leap and stratum used in source selection if they
indicate an unsynchronized source.
Fixes: 2582be8754 ("sources: separate update of leap status")
It is not sufficient to check for disabled server sockets as they are
not open only after the special reference modes end (e.g. initstepslew).
Fixes: 004986310d ("ntp: skip loop test if no server socket is open")
In the NTS-NTP client instance, maintain a local copy of the NTP address
instead of using a pointer to the NCR's address, which may change at
unexpected times.
Also, change the NNC_CreateInstance() to accept only the NTP port to
make it clear the initial NTP address is the same as the NTS-KE address
and to make it consistent with NNC_ChangeAddress(), which accepts only
one address.
Remove stratum from the NTP sample and update it together with the leap
status. This enables a faster update when samples are dropped by the NTP
filters.
Don't accept NTPv4 packets which have a MAC longer than 24 octets to
strictly follow RFC 7822, which specifies the maximum length of a MAC
and the minimum length of the last extension field to avoid an ambiguity
in parsing of the packet.
This removes an ugly hack that was needed to accept packets that
contained one or more extension fields without a MAC, before RFC 7822
was written and NTP implementations started using truncated MACs.
The long MACs were used by chrony in versions 2.x when configured to
authenticate a server or peer with a key using a 256-bit or longer hash
(e.g. SHA256). For compatibility with chrony >= 4.0, these clients/peers
will need to have "version 3" added to the server/peer line in
chrony.conf.
The daemon transmit timestamps are precompensated for the time it takes
to generate a MAC using a symmetric key (as measured on chronyd start)
and also an average round-trip time of the Samba signing of MS-SNTP
responses. This improves accuracy of the transmit timestamp, but it
has some issues.
The correction has a random error which is changing over time due to
variable CPU frequency, system load, migration to a different machine,
etc. If the measured delay is too large, the correction may cause the
transmit timestamp to be later than the actual transmission. Also, the
delay is measured for a packet of a minimal length with no extension
fields, and there is no support for NTS.
Drop the precompensation in favor of the interleaved mode, which now
avoids the authentication delay even when no kernel/hardware timestamps
are available.
If the daemon transmit timestamp is saved for processing of a future
response or responding in the interleaved mode, get a more accurate
timestamp right before calling NIO_SendPacket(). Avoid unnecessary
reading of the clock for the transmit timestamp in the packet (i.e.
in interleaved modes and client basic mode).
This should improve accuracy and stability when authentication is
enabled in the client and symmetric basic modes and also interleaved
modes if kernel/hardware timestamps are not available.
Instead of making the initial burst only once and immediately after
chronyd start (even when iburst is specified together with the offline
option), trigger the burst whenever the connectivity changes from
offline to online.
Refactor the client record and clientlog API to reuse more code between
different services and enumerate the services instead of hardcoding NTP
and cmdmon.
Refactor the code to allow the selection options of the current sources
to be modified when other sources are added and removed. Also, make the
authentication status of each source available to the code which makes
the modifications.
When replacing an NTP source, update the NTS address before the NTP
address to save cookies with the old NTP address instead of the newly
resolved address (which may immediately change to an address provided by
NTS-KE).
Remove leap status from the NTP sample and set it independently from
the sample accumulation in order to accept a leap second sooner when
samples are filtered.
Add an option to enable NTS for an NTP source. Check for NTS-specific
extension fields and pass the packets to the NTS-NTP code in order to
enable the NTS client and server.
